I'm not sure whether this is a known bug or not, but just in case:

I was wandering around the cities rankings (http://codeforces.me/ratings/cities), and when I tried to see the list of members from São Paulo by clicking on it, the system told me that city didn't exist.

I noticed it happens with and only with any city whose name contains diacritics: ´ ~ ^ etc
Examples:
http://codeforces.me/ratings/country/Poland/city/Gdańsk
http://codeforces.me/ratings/country/Brazil/city/São Paulo
http://codeforces.me/ratings/country/Brazil/city/Goiânia

(formatted like this for readability. You can also try http://codeforces.me/ratings/country/Poland/city/Gda%C5%84sk)

PS: The expected behavior is as follows: http://codeforces.me/ratings/country/Russia/city/Moscow

*Edit: Just realized that if you manually switch these characters, you can actually go to the right place! http://codeforces.me/ratings/country/Brazil/city/Sao Paulo ... maybe not too hard to fix :)

struct number{
    int z;
    const bool operator< (const number &that) const{
        return z <= that.z;
    }
}numbers[10000];

int main (){
    for(int i = 0; i < 10000; i++){
        numbers[i].z = 2;
    }
    sort(numbers, numbers+10000);
    return 0;
}

int array[10000];
const bool myfunc (int a, int b){
    return a <= b;
}

int main (){
    for(int i = 0; i < 10000; i++){
        array[i] = 2;
    }
    sort(array, array+10000, myfunc);   
    return 0;
}